Class: Jekyll::MinifyJs

Inherits:
Generator
  • Object
show all
Defined in:
lib/jekyll-minify-js.rb

Overview

MinifyJs is a Jekyll ‘Generator` that minifies JavaScript files found under common asset directories. It prefers the `terser` Ruby gem when available and falls back to an external `terser` CLI when necessary.

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.run(site) ⇒ Object

rubocop:disable Metrics/AbcSize,Metrics/MethodLength,Metrics/CyclomaticComplexity,Metrics/PerceivedComplexity



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# File 'lib/jekyll-minify-js.rb', line 26

def self.run(site) # rubocop:disable Metrics/AbcSize,Metrics/MethodLength,Metrics/CyclomaticComplexity,Metrics/PerceivedComplexity
  # Support both repository-root layout and app/ layout.
  candidates = [
    File.join(site.source, 'assets', 'js'),
    File.join(site.source, 'app', 'assets', 'js')
  ]
  src_dir = candidates.find { |p| Dir.exist?(p) }
  return unless src_dir

  # Read configuration from _config.yml under `minify_js:` key
  cfg = site.config.fetch('minify_js', {})
  return if cfg.key?('enabled') && cfg['enabled'] == false

  dest_dir = File.join(site.dest, cfg.fetch('output_dir', 'assets/js'))
  FileUtils.mkdir_p(dest_dir)

  terser_available = defined?(Terser)

  # Build options from config
  compress_opt = cfg.fetch('compress', true)
  mangle_opt = cfg.fetch('mangle', true)
  source_map_enabled = cfg.fetch('source_map', true)
  exclude_patterns = cfg.fetch('exclude', ['**/*.min.js'])

  Dir.glob(File.join(src_dir, '**', '*.js')).each do |src| # rubocop:disable Metrics/BlockLength
    rel = Pathname.new(src).relative_path_from(Pathname.new(src_dir)).to_s
    out = File.join(dest_dir, rel)
    out_dir = File.dirname(out)
    FileUtils.mkdir_p(out_dir)
    map_name = "#{File.basename(out)}.map"

    # Skip excluded files
    next if exclude_patterns.any? { |pat| File.fnmatch(pat, rel) }

    if terser_available
      Jekyll.logger.info 'Terser:', "minifying #{rel} via terser Ruby gem"
      begin
        src_content = File.open(src, 'r:BOM|UTF-8', &:read)
        options = {}
        options[:compress] = compress_opt
        options[:mangle] = mangle_opt
        if source_map_enabled
          options[:source_map] =
            { filename: File.basename(src), output_filename: File.basename(out), sources_content: true,
              url: map_name }
          compiled, map = Terser.compile_with_map(src_content, options)
        else
          compiled = Terser.compile(src_content, options)
          map = nil
        end
        compiled += "\n//# sourceMappingURL=#{map_name}\n" unless compiled.include?('sourceMappingURL')
        File.write(out, compiled)
        File.write("#{out}.map", map) if map
      rescue StandardError => e
        Jekyll.logger.warn 'Terser:', "ruby terser failed for #{rel}: #{e.message}; copying original"
        FileUtils.cp(src, out)
      end
    else
      terser_cmd = new.detect_terser_cmd
      if terser_cmd
        cmd = %(#{terser_cmd} #{Shellwords.escape(src)} --compress --mangle -o #{Shellwords.escape(out)} --source-map "url='#{map_name}',includeSources") # rubocop:disable Layout/LineLength
        Jekyll.logger.info 'Terser:', "minifying #{rel} via external terser"
        success = system(cmd)
        unless success && File.exist?(out)
          Jekyll.logger.warn 'Terser:', "minify failed for #{rel}; copying original"
          FileUtils.cp(src, out)
        end
      else
        Jekyll.logger.warn 'Terser:', 'no terser available — copying original JS'
        FileUtils.cp(src, out)
      end
    end
  end
end

Instance Method Details

#detect_terser_cmd ⇒ Object 



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# File 'lib/jekyll-minify-js.rb', line 101

def detect_terser_cmd
  # Prefer the bundler-installed terser (from the `terser` gem) via `bundle exec terser`.
  return 'bundle exec terser' if system('bundle exec terser --version > /dev/null 2>&1')
  return 'terser' if system('terser --version > /dev/null 2>&1')

  nil
end

#generate(_site) ⇒ Object 



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# File 'lib/jekyll-minify-js.rb', line 22

def generate(_site)
  # Work is done in the :post_write hook to avoid Jekyll overwriting outputs.
end